Smart leg brace locks and unlocks knee automatically

NeLo is a flexible leg brace that uses sensor data to help polio patients—and people with sports injuries—lock and unlock their knees when walking.

The brace is designed to switch between being flexible and rigid depending on whether the person wearing it is walking, standing, or sitting—when the person's weight needs to be supported on the braced leg it becomes rigid, but it then loosens when the person bends or sits down.

It looks much like a flexible material leg brace, but is connected to two sensors—a foot pressure sensor and a gyroscope worn near the hip—which pair with an Arduino board to analyze the person's position. This data is fed to servo motors that loosen and tighten the material in order to switch between rigid and flexible using a mechanism inspired by a Chinese finger trap. This mechanism, which required the inside of two pieces of fabric to be lined with a sandpaper-like material, allowed for the system to work using relatively small, low-powered motors.

NeLo has an open source design made using BITalino sensors and 3D printed components, in addition to the Arduino. It was designed as part of a competition at an international coding event called Codebits in Portugal by Basilio Vieira, Pedro Leite, and Carolina Correia.

Leite and Vieira had met at a previous Codebits event and planned to collaborate on a project at this year's event. Leite's father suffered from polio as a child and, as a result, had to wear an uncomfortable metal brace. After some research, they discovered that one in 200 polio infections leads to irreversible paralysis (usually in the legs) and that although cases of the disease have decreased by more than 99 percent since 1988, there are still many people living with the crippling after effects.

They met Correia—who helped shape how to communicate the project during the all-important 90-second pitch—at the event. The competition had more than 100 entries but NeLo won overall.

"We developed this as an open hardware solution," Vieira told Wired.co.uk. "We are developing this and giving it to the world to use it as they see fit. This is our contribution for making the world a bit better."

Beyond polio patients, the NeLo could also be used for high performance athletes. "We can modulate the support that NeLo gives, which is good for someone recovering from an injury. The support can be tailored and adapted during the recovery period," Vieira adds.

Celso Martinho, the general manager at SAPO, which organizes Codebits, said that NeLo won for a number of reasons. "It was a unique project because it solves a social problem, it uses a lot of ideas and technology presented at the event, it made use of the partners we had there and it was a good idea." Codebits is a technology event in Lisbon that has taken place for seven years in a row. The three-day event brought together programmers, enthusiasts, and entrepreneurs to take part in demos, workshops, and the competition.